The long range objective of this project is to identify gene products that determine the specialized morphology of a crawling cell and to learn how their activity and localization controls the morphology and motility of the cell. The cell studied is the crawling spermatozoon of the nematode Caenorhabditis elegans. The experimental approach is to dissect morphogenesis genetically and biochemically, starting from both mutants and cloned genes. The current project period focuses on analysis of identified genes that are involved in pseudopod formation during spermiogenesis, since this is the most intriguing, as well as the most accessible, step of sperm morphogenesis. The specific aims are as follows: (1)To complete the molecular cloning and characterization of genes that act during the initial formation of the pseudopod, when the cell's asymmetry is established. These include spe-12 and fer-1, which have already been localized to cloned DNAs; spe-8 and spe-27 which have identical phenotypes to spe-12 ; and spe-6, which appears to control MSP filament assembly in spermatocytes, and might also act during spermiogenesis. (2)To continue to develop in vitro conditions for analysis of MSP assembly to identify functional domains in the protein. To utilize in vitro assembly to see if the gene products that act during pseudopod formation, influence this assembly, and to determine if they bind to MSP filaments or monomers. (3)To complete the characterization of the cloned and sequenced sperm-specific genes found in a cluster on Chromosome IV. This will include antibody localization of their products and identification of mutations in them among recently isolated spe genes that map to this region. (4)To utilize the cloned spe-26 gene, which is efficiently rescued by transformation, to develop a vector for functional disruption of sperm-specific genes with antisense RNA and dominant negative constructs introduced by transformation. To utilize this vector for disrupting the function of the sperm-specific genes already cloned. (5)To interpret this combination of genetic, molecular, biochemical and cellular analyses of mutants to explain how the location of pseudopod formation is established and how MSP filament assembly plays a role in this process and in subsequent motility. This work is of general significance because the mechanisms by which genes specify their morphology and the localization of cell components are fundamental to the differentiation of cells. Understanding these mechanisms may give insight into the genetic basis for the heritable changes in cell shape that invariably accompany malignant transformation as well as genetic defects leading to developmental diseases and birth defects.